Thermal Performance of Green Roof Panels in Sub-Zero Temperatures

To date, much of the research on green roof technology has focused on the capacity for these systems to contribute to the cooling of buildings during summer months. The thermal performance of green roofs in cold climate conditions is critical to understanding the potential of these roofs to decrease energy use in buildings during winter. This paper compares the behavior of two green roof systems with that of a conventional built-up roof by making use of a novel hot box testing apparatus. The green roofs tested are classified as extensive systems. Each system included: a 3 mm thick styrene butadiene rubber waterproofing membrane, 0.2 mm thick polyethylene slip sheet, a 76 mm thick extruded polystyrene insulation layer, 2 mm thick filter fabric, a 51 mm drainage layer followed by a 2 mm thick filter cloth, either 100 mm or 150 mm growing medium, and a 25 mm thick wild flower vegetated mat. The conventional roof consisted of a 2 mm thick layer of Kraft™ vapour retarder bonded with insulation adhesiv...